A novel antibacterial protein capable of inhibiting the growth of plant pathogenic fungi such as Pyricularia orizae and Rhizoctonia solani, which are the two major pathogenic fungi of rice, at a relatively low concentration is detected and identified. Also, the gene of this protein is cloned. This protein is characterized by: being obtained from a fraction of an aqueous extract of a mushroom precipitated by the ammonium sulfate precipitation method; having an antibacterial activity at least on Pyricularia orizae or Rhizoctonia solani; when determined by the gel filtration method, showing a molecular weight of about 210 kD; in the SDS-PAGE method, showing the presence of components of about 50 kD and about 15 kD; sustaining the above antibacterial activity when heated in an aqueous neutral solution at 60 DEG C for 10 minutes; and losing the antibacterial activity when heated in an aqueous neutral solution at 80 DEG C for 10 minutes.